Ambient seismic noise eikonal tomography for near-surface imaging at Valhall

The permanent ocean-bottom array at the Valhall Field in Norway provides an excellent source of passive seismic data to test what might be accomplished with seismic interferometry. The array was installed in 2003 (Kommedal et al., 2004) and data can be recorded for long periods in all weather conditions. The subsurface structure is well known, both from numerous wells and from seismic imaging. During periods without active seismic acquisition at Valhall, there is abundant passive energy in the data over a wide range of fre-quencies.